Telescopic optical imaging system

ABSTRACT

An optical imaging system includes a first lens which has refractive power, a second lens which has refractive power, a third lens which has a convex object-side surface, and an inflection point is formed on an image-side surface thereof, a fourth lens which has refractive power, a fifth lens which has a convex object-side surface, and a sixth lens which has refractive power and an inflection point is formed on an image-side surface thereof, and wherein the first to sixth lens are sequentially disposed from an object side.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation Application of U.S. patentapplication Ser. No. 16/045,866, filed on Jul. 26, 2018, which claimsthe benefit under 35 USC 119(a) of Korean Patent Application No.10-2017-0164905 filed on Dec. 4, 2017 in the Korean IntellectualProperty Office, the entire disclosure of which is incorporated hereinby reference for all purposes.

BACKGROUND 1. Field

The present disclosure relates to a telescopic optical imaging systemincluding six lenses.

2. Description of Related Art

Small camera components may be mounted in mobile communicationterminals. For example, the small camera components may be mounted indevices that have a thin form factor, such as mobile phones, or similardevices. The small camera components may include an optical imagingsystem including a small number of lenses that allow the devices tomaintain their thin form factor. For example, the optical imaging systemof the small camera component may include four or less lenses. However,such an optical imaging system may have a high f-number or focal ratio,such that it may be difficult for the optical imaging system to be usedin a small camera module that has a high performance.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In a general aspect, an optical imaging system includes a first lenswhich has refractive power, a second lens which has refractive power, athird lens which has a convex object-side surface, and an inflectionpoint is formed on an image-side surface thereof, a fourth lens whichhas refractive power, a fifth lens which has a convex object-sidesurface; and a sixth lens which has refractive power, and an inflectionpoint is formed on an image-side surface thereof, wherein the first tosixth lenses are sequentially disposed from an object side.

An inflection point may be formed on an image-side surface of the firstlens.

A sign of refractive power of the second lens may be different from asign of the refractive power of the first lens.

The image-side surface of the third lens may be concave.

The fourth lens may have negative refractive power.

The fifth lens may have negative refractive power.

An image-side surface of the fifth lens may be concave.

The sixth lens may have positive refractive power.

The image-side surface of the sixth lens may be concave.

The optical imaging system may include a stop disposed between the firstlens and the second lens.

In a general aspect, an optical imaging system includes a first lenswhich has refractive power and which has an inflection point formed onan image-side surface thereof, a second lens which has refractive power,a third lens which has refractive power, a fourth lens which hasrefractive power, a fifth lens of which an object-side surface isconvex; and a sixth lens which has refractive power and which has aninflection point formed on an image-side surface thereof, wherein thefirst to sixth lenses are sequentially disposed from an object side.

An inflection point may be formed on an image-side surface of the thirdlens.

An f-number of the optical imaging system may be 2.0 or less.

An entire field of view (FOV) of the optical imaging system may be 80°or more.

In the optical imaging system, TTL/f<1.2 in which TTL is a distance froman object-side surface of the first lens to an imaging plane, and f isan overall focal length of the optical imaging system.

In the optical imaging system, f1/f<1.0 in which f is an overall focallength of the optical imaging system, and f1 is a focal length of thefirst lens.

In a general aspect, an optical imaging system includes a first lenswhich has a positive refractive power and a convex object-side surface,a second lens which has a negative refractive power and a convexobject-side surface, a third lens which has a positive refractive power,a convex object-side surface, and an inflection point formed on animage-side surface, a fourth lens which has a negative refractive powerand a concave image-side surface, a fifth lens which has a negativerefractive power, and a sixth lens which has a positive refractive powerand a concave image-side surface, wherein the first to sixth lenses aresequentially disposed from an object side.

The first lens may have a concave image-side surface.

Inflection points may be formed on the image-side surface of the firstlens.

The fifth lens and/or the sixth lens may have inflection points on theimage-side surface and the object-side surface.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a view illustrating a first example of an optical imagingsystem;

FIG. 2 illustrates graphs representing aberration curves of the opticalimaging system illustrated in FIG. 1;

FIG. 3 is a view illustrating a second example of an optical imagingsystem;

FIG. 4 illustrates graphs representing aberration curves of the opticalimaging system illustrated in FIG. 3;

FIG. 5 illustrates a third example of an optical imaging system; and

FIG. 6 illustrates graphs representing aberration curves of the opticalimaging system illustrated in FIG. 5.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.In the drawings, for example, due to manufacturing techniques and/ortolerances, modifications of the shape shown may be estimated. Thus, theexamples described herein should not be construed as being limited tothe particular shapes of regions shown herein, for example, the examplesdescribed herein include a change in shape as a result of manufacturing.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

Throughout the specification, when an element, such as a layer, region,or substrate, is described as being “on,” “connected to,” or “coupledto” another element, it may be directly “on,” “connected to,” or“coupled to” the other element, or there may be one or more otherelements intervening therebetween. In contrast, when an element isdescribed as being “directly on,” “directly connected to,” or “directlycoupled to” another element, there can be no other elements interveningtherebetween.

As used herein, the term “and/or” includes any one and any combinationof any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used hereinto describe various members, components, regions, layers, or sections,these members, components, regions, layers, or sections are not to belimited by these terms. Rather, these terms are only used to distinguishone member, component, region, layer, or section from another member,component, region, layer, or section. Thus, a first member, component,region, layer, or section referred to in examples described herein mayalso be referred to as a second member, component, region, layer, orsection without departing from the teachings of the examples.

Spatially relative terms such as “above,” “upper,” “below,” and “lower”may be used herein for ease of description to describe one element'srelationship to another element as shown in the figures. Such spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,an element described as being “above” or “upper” relative to anotherelement will then be “below” or “lower” relative to the other element.Thus, the term “above” encompasses both the above and below orientationsdepending on the spatial orientation of the device. The device may alsobe oriented in other ways (for example, rotated 90 degrees or at otherorientations), and the spatially relative terms used herein are to beinterpreted accordingly.

The terminology used herein is for describing various examples only, andis not to be used to limit the disclosure. The articles “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes,”and “has” specify the presence of stated features, numbers, operations,members, elements, and/or combinations thereof, but do not preclude thepresence or addition of one or more other features, numbers, operations,members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of theshapes shown in the drawings may occur. Thus, the examples describedherein are not limited to the specific shapes shown in the drawings, butinclude changes in shape that occur during manufacturing.

In addition, in the various examples, a first lens may refer to a lensclosest to an object (or a subject) being imaged, while a sixth lens mayrefer to a lens closest to an imaging plane (or an image sensor). Inaddition, all of radii of curvature and thicknesses of lenses, athrough-the-lens (TTL) metering, an IMG HT (a half of a diagonal lengthof the imaging plane), and focal lengths of the lenses may berepresented by millimeters (mm). Further, thicknesses of the lenses,gaps between the lenses, and the TTL metering may be distancescalculated on the basis of optical axes of the lenses. When describingthe shapes of the lenses, a notation that one surface of a lens isconvex means that an optical axis portion of a corresponding surface isconvex, and a notation that one surface of a lens is concave means thatan optical axis portion of a corresponding surface is concave.Therefore, although the description may note that one surface of a lensis convex, an edge portion of the same lens may be concave. Similarly,although a description may note that one surface of a lens is concave,an edge portion of the same lens may be convex.

An optical imaging system may include six lenses. For example, theoptical imaging system may include a first lens, a second lens, a thirdlens, a fourth lens, a fifth lens, and a sixth lens that aresequentially disposed from an object side. The first to sixth lenses maybe disposed with an air interval between each of the lenses. Forexample, an image-side surface of one of neighboring lenses and anobject-side surface of the other lens may not be in contact with eachother.

In an example, the first lens may have refractive power. For example,the first lens may have positive refractive power. One surface of thefirst lens may be convex. For example, an object-side surface of thefirst lens may be convex. Inflection points may be formed on the firstlens. For example, one or more inflection points may be formed on animage-side surface of the first lens.

In an example, the first lens may have an aspherical surface. Forexample, both surfaces of the first lens may be aspherical. The firstlens may be formed of a material having high light transmissivity andexcellent workability. For example, the first lens may be formed ofplastic. However, a material of the first lens is not limited to theplastic. For example, the first lens may be formed of glass. The firstlens may have a small refractive index. For example, the refractiveindex of the first lens may be less than 1.6, but is not limitedthereto.

In an example, the second lens may have refractive power. For example,the second lens may have negative refractive power. One surface of thesecond lens may be convex. For example, an object-side surface of thesecond lens may be convex.

In an example, the second lens may have an aspherical surface. Forexample, an object-side surface of the second lens may be aspherical.The second lens may be formed of a material having high lighttransmissivity and excellent workability. For example, the second lensmay be formed of plastic. However, a material of the second lens is notlimited to the plastic. For example, the second lens may also be formedof glass. The second lens may have a refractive index greater than thatof the first lens. For example, the refractive index of the second lensmay be 1.65 or more, but is not limited thereto.

In an example, the third lens may have refractive power. For example,the third lens may have positive refractive power. One surface of thethird lens may be convex. For example, an object-side surface of thethird lens may be convex. Inflection points may be formed on the thirdlens. For example, one or more inflection points may be formed on animage-side surface of the third lens.

In an example, the third lens may have an aspherical surface. Forexample, both surfaces of the third lens may be aspherical. The thirdlens may be formed of a material having high light transmissivity andexcellent workability. For example, the third lens may be formed ofplastic. However, a material of the third lens is not limited to theplastic. For example, the third lens may be formed of glass. The thirdlens may have a refractive index smaller than that of the second lens.For example, the refractive index of the third lens may be less than1.6, but is not limited thereto.

In an example, the fourth lens may have refractive power. For example,the fourth lens may have negative refractive power. One surface of thefourth lens may be concave. For example, an image-side surface of thefourth lens may be concave.

In an example, the fourth lens may have an aspherical surface. Forexample, an object-side surface of the fourth lens may be spherical, andan image-side surface thereof may be aspherical. The fourth lens may beformed of a material having high light transmissivity and excellentworkability. For example, the fourth lens may be formed of plastic.However, a material of the fourth lens is not limited to the plastic.For example, the fourth lens may be formed of glass. The fourth lens mayhave a refractive index greater than that of the third lens. Forexample, the refractive index of the fourth lens may be 1.6 or more, butis not limited thereto.

In an example, the fifth lens may have refractive power. For example,the fifth lens may have negative refractive power. One surface of thefifth lens may be convex. For example, an object-side surface of thefifth lens may be convex. The fifth lens may have an inflection point.For example, an inflection point may be formed on at least one of theobject-side surface and an image-side surface of the fifth lens.

In an example, the fifth lens may have an aspherical surface. Forexample, both surfaces of the fifth lens may be aspherical. The fifthlens may be formed of a material having high light transmissivity andexcellent workability. For example, the fifth lens may be formed ofplastic. However, a material of the fifth lens is not limited to theplastic. For example, the fifth lens may be formed of glass. The fifthlens may have a refractive index that is substantially similar to thatof the fourth lens. For example, the refractive index of the fifth lensmay be 1.6 or more, but is not limited thereto.

In an example, the sixth lens may have refractive power. For example,the sixth lens may have positive refractive power. One surface of thesixth lens may be concave. For example, an image-side surface of thesixth lens may be concave. The sixth lens may have an inflection point.For example, an inflection point may be formed on at least one of anobject-side surface and an image-side surface of the sixth lens.

In an example, the sixth lens may have an aspherical surface. Forexample, both surfaces of the sixth lens may be aspherical. The sixthlens may be formed of a material having high light transmissivity andexcellent workability. For example, the sixth lens may be formed ofplastic. However, a material of the sixth lens is not limited to theplastic. For example, the sixth lens may be formed of glass. The sixthlens may have a refractive index greater than that of the fifth lens.For example, the refractive index of the sixth lens may be less than1.6, but is not limited thereto.

The aspherical surfaces of the first to sixth lenses may be representedby the following Equation 1:

$\begin{matrix}{Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {Ar}^{4} + {Br}^{6} + {Cr}^{8} + {Dr}^{10} + {Er}^{12} + {Fr}^{14} + {Gr}^{16} + {Hr}^{18} + {{Jr}^{20}.}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Here, c is an inverse of a radius of curvature of the lens, k is a conicconstant, r is a distance from a certain point on an aspherical surfaceof the lens to an optical axis, A to J are aspherical constants, and Z(or SAG) is a distance between the certain point on the asphericalsurface of the lens at the distance r and a tangential plane meeting theapex of the aspherical surface of the lens.

The optical imaging system may further include a filter, an imagesensor, and a stop.

The filter may be disposed between the sixth lens and the image sensor.The filter may block some wavelengths of light. For example, the filtermay block an infrared wavelength of light.

The image sensor may form the imaging plane. For example, a surface ofthe image sensor may form the imaging plane.

The stop may be disposed in order to control an amount of light incidentto the lenses. For example, the stop may be disposed between the firstand second lenses.

The optical imaging system may satisfy the following ConditionalExpressions:

F No.<2.0  Conditional Expression 1

80<FOV  Conditional Expression 2

TTL/f<1.2  Conditional Expression 3

f1/f<1.0  Conditional Expression 4

4.0<D34/D12  Conditional Expression 5

1.0<D34/D23  Conditional Expression 6

0.8<D34/D45<1.0  Conditional Expression 7

6.0<|R7/R8|  Conditional Expression 8

20<f6/f1.  Conditional Expression 9

Here, TTL is a distance from the object-side surface of the first lensto the imaging plane, f is an overall focal length of the opticalimaging system, D12 is a distance from the image-side surface of thefirst lens to the object-side surface of the second lens, D23 is adistance from an image-side surface of the second lens to theobject-side surface of the third lens, D34 is a distance from theimage-side surface of the third lens to the object-side surface of thefourth lens, D45 is distance from the image-side surface of the fourthlens to the object-side surface of the fifth lens, R7 is a radius ofcurvature of the object-side surface of the fourth lens, R8 is a radiusof curvature of the image-side surface of the fourth lens, f1 is a focallength of the first lens, and f6 is a focal length of the sixth lens.

Next, optical imaging systems according to various examples will bedescribed.

An example of optical imaging system will be described with reference toFIG. 1.

The optical imaging system 100 according to the example may include afirst lens 110, a second lens 120, a third lens 130, a fourth lens 140,a fifth lens 150, and a sixth lens 160.

The first lens 110 may have positive refractive power, and anobject-side surface thereof may be convex and an image-side surfacethereof may be concave. Inflection points may be formed on theimage-side surface of the first lens 110. The second lens 120 may havenegative refractive power, and an object-side surface thereof may beconvex and an image-side surface thereof may be concave. The third lens130 may have positive refractive power, and an object-side surfacethereof may be convex and an image-side surface thereof may be concave.Inflection points may be formed on the image-side surface of the thirdlens 130. The fourth lens 140 may have negative refractive power, and anobject-side surface thereof may be convex and an image-side surfacethereof may be concave. The fifth lens 150 may have negative refractivepower, and an object-side surface thereof may be convex and animage-side surface thereof may be concave. Inflection points may beformed on both surfaces of the fifth lens 150. The sixth lens 160 mayhave positive refractive power, and an object-side surface thereof maybe convex and an image-side surface thereof may be concave. Inflectionpoints may be formed on both surfaces of the sixth lens 160.

The optical imaging system 100 may further include a filter 170, animage sensor 180, and a stop ST. The filter 170 may be disposed betweenthe sixth lens 160 and the image sensor 180, and the stop ST may bedisposed between the first lens 110 and the second lens 120.

The optical imaging system configured as described above may representaberration characteristics as illustrated in FIG. 2. Characteristics oflenses and aspherical values of the optical imaging system according tothe examples are represented by Table 1 and Table 2.

TABLE 1 First Example f = 4.120 F No. = 1.99 FOV = 83.14 TLL = 4.665Surface Radius of Thickness/ Refractive Abbe Effective Focal No.Curvature Distance Index Number Diameter Length S1  First Lens 1.43660.6149 1.546 56.11 1.06 3.299 S2  6.0246 0.0637 1.00 S3  Second Lens32.9400 0.2300 1.667 20.35 0.95 −10.055 S4  5.5563 0.2053 0.85 S5  ThirdLens 6.3389 0.3030 1.546 56.11 090 25.932 S6  11.4580 0.3174 0.97 S7 Fourth Lens 188.5888 0.2500 1.667 20.35 1.07 −22.622 S8  13.9623 0.34711.37 S9  Fifth Lens 12.9145 0.6132 1.656 21.53 1.58 −16.710 S10 5.81640.1000 2.03 S11 Sixth Lens 1.6520 0.5937 1.536 55.65 2.61 1333.279 S121.4482 0.1080 2.80 S13 Filter infinity 0.1100 1.518 64.20 3.26 S14infinity 0.7087 3.30 S15 Imaging infinity 0.0100 3.73 Plane

TABLE 2 First Example S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 Radius of1.437 6.025 32.940 5.556 6.339 11.458 188.589 13.962 12.914 5.816 1.6521.448 Curvature K −0.328 0.979 −0.947 1.000 −1.000 0.000 0.953 13.4432.121 −14.908 −2.928 −1.005 A 0.005 −0.047 −0.010 0.018 −0.101 −0.048−0.104 −0.085 0.077 −0.087 −0.412 −0.321 B 0.008 −0.103 −0.059 0.1150.322 −0.133 −0.207 −0.293 −0.359 0.011 0.242 0.179 C 0.039 0.420 0.488−0.330 −2.074 0.589 0.588 0.796 0.431 0.019 −0.077 −0.076 D −0.236−0.994 −1.140 0.997 6.309 −1.932 −0.573 −1.059 −0.32 −0.020 0.01 0.02 E0.434 1.244 1.402 −1.581 −10.659 3.328 −0.556 0.762 0.126 0.008 −0.002−0.004 F −0.377 −0.780 −0.793 1.199 9.231 −2.982 1.608 −0.276 −0.021−0.002 0.000 0.000 G 0.114 0.193 0.172 −0.194 −3.033 1.152 −1.287 0.0390.001 0.000 0.000 0.000 H 0 0 0 0 0 0.364 0 0 0 0 0 0.000

An example of an optical imaging system will be described with referenceto FIG. 3.

In a second example, the optical imaging system 200 may include a firstlens 210, a second lens 220, a third lens 230, a fourth lens 240, afifth lens 250, and a sixth lens 260.

The first lens 210 may have positive refractive power, and anobject-side surface thereof may be convex and an image-side surfacethereof may be concave. Inflection points may be formed on theimage-side surface of the first lens 210. The second lens 220 may havenegative refractive power, and an object-side surface thereof may beconvex and an image-side surface thereof may be concave. The third lens230 may have positive refractive power, and an object-side surfacethereof may be convex and an image-side surface thereof may be concave.Inflection points may be formed on the image-side surface of the thirdlens 230. The fourth lens 240 may have negative refractive power, and anobject-side surface thereof may be concave and an image-side surfacethereof may be concave. The fifth lens 250 may have negative refractivepower, and an object-side surface thereof may be convex and animage-side surface thereof may be concave. Inflection points may beformed on both surfaces of the fifth lens 250. The sixth lens 260 mayhave positive refractive power, and an object-side surface thereof maybe convex and an image-side surface thereof may be concave. Inflectionpoints may be formed on both surfaces of the sixth lens 260.

The optical imaging system 200 may further include a filter 270, animage sensor 280, and a stop ST. The filter 270 may be disposed betweenthe sixth lens 260 and the image sensor 280, and the stop ST may bedisposed between the first lens 210 and the second lens 220.

The optical imaging system configured as described above may representaberration characteristics as illustrated in FIG. 4. Characteristics oflenses and aspherical values of the optical imaging system according tothe second example are represented by Table 3 and Table 4.

TABLE 3 Second Example f = 4.110 F No. = 1.97 FOV = 83.22 TLL = 4.665Surface Radius of Thickness/ Refractive Abbe Effective Focal No.Curvature Distance Index Number Diameter Length S1  First Lens 1.44030.6343 1.546 56.11 1.06 3.302 S2  6.0250 0.0519 1.00 S3  Second Lens31.3219 0.2300 1.667 20.35 0.96 −10.256 S4  5.6099 0.2121 0.85 S5  Thirdlens 6.3042 0.3033 1.546 56.11 0.88 25.234 S6  11.4156 0.3198 0.95 S7 Fourth Lens −100.0127 0.2600 1.667 20.35 1.05 −20.097 S8  15.5410 0.33491.34 S9  Fifth Lens 12.3924 0.6026 1.656 21.53 1.53 −15.269 S10 5.43870.1000 2.00 S11 Sixth Lens 1.5788 0.5863 1.536 55.65 2.60 87.816 S121.4217 0.6206 2.78 S13 Filter infinity 0.1100 1.518 64.20 3.50 S14infinity 0.2880 3.54 S15 Imaging Plane infinity 0.0120 3.73

TABLE 4 Second Example S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 Radius of1.440 6.025 31.322 5.610 6.304 11.416 −100.013 15.541 12.392 5.439 1.5791.422 Curvature K −0.332 0.979 −0.947 1.000 −1.000 0.000 0.953 13.4432.121 −14.908 −2.967 −1.009 A −0.002 −0.051 −0.006 0.018 −0.095 −0.052−0.110 −0.086 0.084 −0.101 −0.429 −0.332 B 0.063 −0.082 −0.068 0.1600.281 −0.083 −0.157 −0.271 −0.383 0.027 0.254 0.189 C −0.177 0.272 0.443−0.629 −1.863 0.351 0.412 0.748 0.485 0.012 −0.081 −0.082 D 0.233 −0.546−0.890 1.928 5.673 −1.336 −0.139 −1.007 −0.38 −0.019 0.02 0.02 E −0.1290.586 0.925 −3.155 −9.587 2.496 −1.346 0.731 0.160 0.009 −0.002 −0.005 F−0.026 −0.293 −0.370 2.573 8.297 −2.374 2.520 −0.266 −0.031 −0.002 0.0000.001 G 0.026 0.048 0.027 −0.690 −2.718 0.970 −1.865 0.038 0.002 0.0000.000 0.000 M 0 0 0 0 0 0 0.514 0 0 0 0 0.000

A third example of an optical imaging system will be described withreference to FIG. 5.

In an example, the optical imaging system 300 may include a first lens310, a second lens 320, a third lens 330, a fourth lens 340, a fifthlens 350, and a sixth lens 360.

In an example, the first lens 310 may have positive refractive power,and an object-side surface thereof may be convex and an image-sidesurface thereof may be concave. Inflection points may be formed on theimage-side surface of the first lens 310. The second lens 320 may havenegative refractive power, and an object-side surface thereof may beconvex and an image-side surface thereof may be concave. The third lens330 may have positive refractive power, and an object-side surfacethereof may be convex and an image-side surface thereof may be concave.Inflection points may be formed on the image-side surface of the thirdlens 330. The fourth lens 340 may have negative refractive power, and anobject-side surface thereof may be concave and an image-side surfacethereof may be concave. The fifth lens 350 may have negative refractivepower, and an object-side surface thereof may be convex and animage-side surface thereof may be concave. Inflection points may beformed on both surfaces of the fifth lens 350. The sixth lens 360 mayhave positive refractive power, and an object-side surface thereof maybe convex and an image-side surface thereof may be concave. Inflectionpoints may be formed on both surfaces of the sixth lens 360.

The optical imaging system 300 may further include a filter 370, animage sensor 380, and a stop ST. The filter 370 may be disposed betweenthe sixth lens 360 and the image sensor 380, and the stop ST may bedisposed between the first lens 310 and the second lens 320.

The optical imaging system configured as described above may representaberration characteristics as illustrated in FIG. 6. Characteristics oflenses and aspherical values of the optical imaging system according tovarious examples are represented by Table 5 and Table 6.

TABLE 5 Third Example f = 4.110 F No. = 1.98 FOV = 83.25 TLL = 4.665Surface Radius of Thickness/ Refractive Abbe Effective Focal No.Curvature Distance Index Number Diameter Length S1  First Lens 1.44670.6342 1.545 56.11 1.06 3.291 S2  6.2504 0.0520 1.00 S3  Second Lens31.5159 0.2300 1.667 20.35 0.96 −10.084 S4  5.5384 0.2113 0.85 S5  ThirdLens 6.2696 0.2975 1.546 56.11 0.87 26.329 S6  10.9247 0.3253 0.95 S7 Fourth Lens −146.5455 0.2600 1.667 20.35 1.06 −20.784 S8  15.3654 0.33751.35 S9  Fifth Lens 11.4177 0.5972 1.656 21.53 1.58 −15.860 S10 5.33660.1000 2.01 S11 Sixth Lens 1.5986 0.5900 1.536 55.65 2.63 105.080 S121.4332 0.1980 2.80 S13 Filter infinity 0.1100 1.518 64.20 3.25 S14infinity 0.7107 3.29 S15 Imaging Plane infinity 0.0120 3.74

TABLE 6 Third Example S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 Radius of1.447 6.250 31.516 6.538 6.270 10.925 −146.546 15.365 11.418 6.337 1.6991.433 Curvature K −0.334 0.979 −0.947 1.000 −1.000 0.000 0.953 13.4432.121 −14.908 −2.897 −1.007 A 0.004 −0.045 −0.007 0.023 −0.096 −0.052−0.109 −0.088 0.084 −0.092 −0.424 −0.328 B 0.015 −0.164 −0.083 0.0820.281 −0.103 −0.180 −0.274 −0.382 0.015 0.248 0.185 C 0.001 0.640 0.558−0.117 −1.902 0.455 0.490 0.749 0.478 0.019 −0.077 −0.080 D −0.129−1.340 −1.162 0.255 5.899 −1.604 −0.261 −0.997 −0.38 −0.022 0.01 0.02 E0.276 1.515 1.240 −0.292 −10.097 2.896 −1.271 0.715 0.159 0.009 −0.002−0.005 F −0.260 −0.869 −0.565 0.078 8.803 −2.703 2.562 −0.258 −0.032−0.002 0.000 0.001 G 0.080 0.197 0.079 0.181 −2.899 1.086 −1.948 0.0360.002 0.000 0.000 0.000 H 0 0 0 0 0 0 0.546 0 0 0 0 0.000

Table 7 represents examples of values of Conditional Expressions of theoptical imaging systems.

TABLE 7 Conditional First Second Third. Expression Example ExampleExample F No. 1.990 1.970 1.980 FOV 83.14 83.22 83.25 TTL/f 1.132 1.1351.135 f1/f 0.801 0.803 0.801 D34/D12 4.982 6.165 6.252 D34/D23 1.5461.508 1.539 D34/D45 0.914 0.955 0.964 |R7/R8| 13.507 6.435 9.537 f6/f1404.11 26.59 31.93 f3/f1 7.860 7.642 8.000 f3/f4 −1.146 −1.256 −1.267

As set forth in the examples above, an optical imaging systemappropriate for a small camera component having high performance may beimplemented.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure

What is claimed is:
 1. An optical imaging system comprising: a firstlens comprising positive refractive power and a convex object-sidesurface; a second lens comprising negative refractive power and a convexobject-side surface; a third lens comprising a convex object-sidesurface and a concave image-side surface; a fourth lens comprisingnegative refractive power, a convex object-side surface, and a concaveimage-side surface; a fifth lens comprising a convex object-sidesurface; and a sixth lens comprising positive refractive power, whereinthe first to sixth lenses are sequentially disposed from an object side.2. The optical imaging system of claim 1, wherein the second lens has aconcave image-side surface.
 3. The optical imaging system of claim 1,wherein the fifth lens has a concave image-side surface.
 4. The opticalimaging system of claim 1, wherein the sixth lens has a convexobject-side surface.
 5. The optical imaging system of claim 1, whereinthe fifth lens has negative refractive power.
 6. The optical imagingsystem of claim 1, wherein TTL/f<1.2 in which TTL is a distance from anobject-side surface of the first lens to an imaging plane, and f is anoverall focal length of the optical imaging system.
 7. The opticalimaging system of claim 1, wherein f1/f<1.0 in which f is an overallfocal length of the optical imaging system, and f1 is a focal length ofthe first lens.
 8. An optical imaging system comprising: a first lenscomprising positive refractive power and a convex object-side surface; asecond lens comprising negative refractive power and a convexobject-side surface; a third lens comprising a convex object-sidesurface and a concave image-side surface; a fourth lens comprisingnegative refractive power, a convex object-side surface, and a concaveimage-side surface; a fifth lens comprising a convex object-sidesurface; and a sixth lens comprising a concave image-side surface,wherein the first to sixth lenses are sequentially disposed from anobject side, and wherein an f-number of the optical imaging system is2.0 or less.
 9. The optical imaging system of claim 8, wherein the firstlens has a concave image-side surface.
 10. The optical imaging system ofclaim 8, wherein the second lens has a concave image-side surface. 11.The optical imaging system of claim 8, wherein the third lens haspositive refractive power.
 12. The optical imaging system of claim 8,wherein an inflection point is formed on an image-side surface of thethird lens.
 13. The optical imaging system of claim 8, wherein the sixthlens has a concave image-side surface.
 14. The optical imaging system ofclaim 8, wherein TTL/f<1.2 in which TTL is a distance from anobject-side surface of the first lens to an imaging plane, and f is anoverall focal length of the optical imaging system.
 15. The opticalimaging system of claim 8, wherein f1/f<1.0 in which f is an overallfocal length of the optical imaging system, and f1 is a focal length ofthe first lens.